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15311. The 4 brightest red giants in the UFD galaxy Ret 2
ID:
ivo://CDS.VizieR/J/AJ/151/82
Title:
The 4 brightest red giants in the UFD galaxy Ret 2
Short Name:
J/AJ/151/82
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ultra-faint dwarf (UFD) galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey (Diehl et al. 2014SPIE.9149E..0VD). We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/Magellan Fiber System. We present detailed abundances for as many as 20 elements per star, including 12 elements heavier than the Fe group. We confirm previous detection of high levels of r-process material in Ret 2 (mean [Eu/Fe]=+1.69+/-0.05) found in three of these stars (mean [Fe/H]=-2.88+/-0.10). The abundances closely match the r-process pattern found in the well-studied metal-poor halo star CS 22892-052. Such r-process-enhanced stars have not been found in any other UFD galaxy, though their existence has been predicted by at least one model. The fourth star in Ret 2 ([Fe/H]=-3.42+/-0.20) contains only trace amounts of Sr ([Sr/Fe]=-1.73+/-0.43) and no detectable heavier elements. One r-process enhanced star is also enhanced in C (natal [C/Fe]~+1.1). This is only the third such star known, which suggests that the nucleosynthesis sites leading to C and r-process enhancements are decoupled. The r-process-deficient star is enhanced in Mg ([Mg/Fe]=+0.81+/-0.14), and the other three stars show normal levels of {alpha}-enhancement (mean [Mg/Fe]=+0.34+/-0.03). The abundances of other {alpha} and Fe-group elements closely resemble those in UFD galaxies and metal-poor halo stars, suggesting that the nucleosynthesis that led to the large r-process enhancements either produced no light elements or produced light-element abundance signatures indistinguishable from normal supernovae.
15312. The BUD sample. I. L dwarf activity sample
ID:
ivo://CDS.VizieR/J/AJ/149/158
Title:
The BUD sample. I. L dwarf activity sample
Short Name:
J/AJ/149/158
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the colors and activity of ultracool (M7-L8) dwarfs from the Tenth Data Release of the Sloan Digital Sky Survey (SDSS). We combine previous samples of SDSS M and L dwarfs with new data obtained from the Baryon Oscillation Sky Survey (BOSS) to produce the BOSS Ultracool Dwarf (BUD) sample of 11820 M7-L8 dwarfs. By combining SDSS data with photometry from 2MASS and the Wide-field Infrared Sky Explorer (WISE) mission, we present ultracool dwarf colors from i-z to W2-W3 as a function of spectral type, and extend the SDSS-2MASS-WISE color locus to include ultracool dwarfs. The i-z, i-J, and z-J colors provide the best indication of spectral type for M7-L3 dwarfs. We also examine ultracool dwarf chromospheric activity through the presence and strength of H{alpha} emission. The fraction of active dwarfs rises through the M spectral sequence until it reaches ~90% at spectral type L0. The fraction of active dwarfs then declines to 50% at spectral type L5; no H{alpha} emission is observed in the late-L dwarfs in the BUD sample. The fraction of active L0-L5 dwarfs is much higher than previously observed. The strength of activity declines with spectral type from M7 through L3, after which the data do not show a clear trend. Using one-dimensional chromosphere models, we explore the range of filling factors and chromospheric temperature structures that are consistent with H{alpha} observations of M0-L7 dwarfs. M dwarf chromospheres have a similar, smoothly varying range of temperature and surface coverage, while L dwarf chromospheres are cooler and have smaller filling factors.
15313. The B3-VLA Quasar Sample
ID:
ivo://CDS.VizieR/J/A+AS/123/219
Title:
The B3-VLA Quasar Sample
Short Name:
J/A+AS/123/219
Date:
21 Oct 2021
Publisher:
CDS
Description:
A new low frequency radio selected Sample of 125 Quasars complete down to 100mJy at 408MHz is presented in this paper. The sample is a part of the B3-VLA sample: 1050 radiosources selected from the B3 catalogue at 408MHz and observed at the VLA (1465MHz, C and A configurations). Out of the 352 sources, identified on the POSS-I down to m_r_~20.0, 172 are quasar candidates. In this paper we give the final assessment of the quasar sample from spectroscopic observations of the candidates. The final complete quasar sample consists of 125 objects. Furthermore 3 Bl Lac objects have been identified and two Bl Lac candidates.
15314. The Canada-France Redshift Survey (CFRS)
ID:
ivo://CDS.VizieR/VII/225B
Title:
The Canada-France Redshift Survey (CFRS)
Short Name:
VII/225B
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Canada-France Redshift Survey (CFRS) is a collaboration between astronomers in Canada and France: Simon Lilly (University of Toronto), Olivier Le Fevre and Francois Hammer (Observatoire de Paris Meudon), David Crampton (Dominion Astrophysical Observatory, Victoria), Laurence Tresse (Cambridge University), and David Schade and Dan Hudon (University of Toronto). The survey is based primarily on observations with the 3.6m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea, Hawaii. The CFRS consists of spectra of over 1000 faint objects selected to have 17.5 < I(AB) < 22.5 in five regions of sky. The survey is providing the first systematic study of normal galaxies at redshifts z > 0.5, corresponding to look-back times of greater than 50% of the age of the Universe. Observations of CFRS galaxies have also been made with the Hubble Space Telescope and the survey will form the basis of future studies with a number of other ground-based and space facilities. We have written a lay-persons guide to the CFRS and the main scientific results that are emerging from it.
15315. The 3C and 3CR Catalogues
ID:
ivo://CDS.VizieR/VIII/1A
Title:
The 3C and 3CR Catalogues
Short Name:
VIII/1A
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 3C Catalog is the result of observations with the Cambridge four-element interferometer at a frequency of 159MHz, and contains 471 sources between declinations -22 and +71degrees, with a flux density larger than 8Jy. The Revised version of the 3C (3CR) is based on new observations at a frequency of 178MHz, and represents a survey of all sources North of -05degrees with a flux density brighter than 9Jy, except in the areas near the ridge of galactic emission. The original numbering system has been preserved.
15316. The 5C6 and 5C7 surveys of radio sources.
ID:
ivo://CDS.VizieR/J/MNRAS/182/273
Title:
The 5C6 and 5C7 surveys of radio sources.
Short Name:
J/MNRAS/182/273
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalog contains the 5C6 and 5C7 radio surveys at 408 and 1407 MHz done with the with the One-Mile telescope at Cambridge (UK). The 5C6 survey of radio sources, made at 408 MHz (HPBW 80"x151") and 1407 MHz (HPBW 23"x44") was centered on 02:14 +32:00' (B1950) and contains 297 sources stronger than 10 mJy at 408 MHz and 1.5 mJy at 1407 MHz. The flux densities are on the KPW scale (Kellermann et al. 1969ApJ...157....1K) and were based on 3C147 and 3C380. Positions, positional errors, flux density information, and descriptions of optical objects visible on the Palomar Sky Survey within about 20" of the radio sources are given. The 5C7 survey of radio sources, made at 408 MHz (HPBW 80"x176") and 1407 MHz (HPBW 23"x51") was centered at 08:17 +27:00 (B1950) and contains 281 sources stronger than 10 mJy at 408 MHz and 1.5 mJy at 1407 MHz. The flux densities are on the KPW scale (Kellermann et al. 1969ApJ...157....1K), and were based on 3C147 and 3C380. Positions, positional errors, flux density information, and descriptions of optical objects visible on the Palomar Sky Survey within about 20" of the radio sources are given.
15317. The Cannon: a new approach to determine abundances
ID:
ivo://CDS.VizieR/J/ApJ/808/16
Title:
The Cannon: a new approach to determine abundances
Short Name:
J/ApJ/808/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
New spectroscopic surveys offer the promise of stellar parameters and abundances ("stellar labels") for hundreds of thousands of stars; this poses a formidable spectral modeling challenge. In many cases, there is a subset of reference objects for which the stellar labels are known with high(er) fidelity. We take advantage of this with The Cannon, a new data-driven approach for determining stellar labels from spectroscopic data. The Cannon learns from the "known" labels of reference stars how the continuum-normalized spectra depend on these labels by fitting a flexible model at each wavelength; then, The Cannon uses this model to derive labels for the remaining survey stars. We illustrate The Cannon by training the model on only 542 stars in 19 clusters as reference objects, with Teff, logg, and [Fe/H] as the labels, and then applying it to the spectra of 55000 stars from APOGEE DR10. The Cannon is very accurate. Its stellar labels compare well to the stars for which APOGEE pipeline (ASPCAP) labels are provided in DR10, with rms differences that are basically identical to the stated ASPCAP uncertainties. Beyond the reference labels, The Cannon makes no use of stellar models nor any line-list, but needs a set of reference objects that span label-space. The Cannon performs well at lower signal-to-noise, as it delivers comparably good labels even at one-ninth the APOGEE observing time. We discuss the limitations of The Cannon and its future potential, particularly, to bring different spectroscopic surveys onto a consistent scale of stellar labels.
15318. The Cannon: a new approach to determine masses
ID:
ivo://CDS.VizieR/J/ApJ/823/114
Title:
The Cannon: a new approach to determine masses
Short Name:
J/ApJ/823/114
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mass of a star is arguably its most fundamental parameter. For red giant stars, tracers luminous enough to be observed across the Galaxy, mass implies a stellar evolution age. It has proven to be extremely difficult to infer ages and masses directly from red giant spectra using existing methods. From the Kepler and APOGEE surveys, samples of several thousand stars exist with high-quality spectra and asteroseismic masses. Here we show that from these data we can build a data-driven spectral model using The Cannon, which can determine stellar masses to ~0.07dex from APOGEE DR12 spectra of red giants; these imply age estimates accurate to ~0.2dex (40%). We show that The Cannon constrains these ages foremost from spectral regions with CN absorption lines, elements whose surface abundances reflect mass-dependent dredge-up. We deliver an unprecedented catalog of 70000 giants (including 20000 red clump stars) with mass and age estimates, spanning the entire disk (from the Galactic center to R~20kpc). We show that the age information in the spectra is not simply a corollary of the birth-material abundances [Fe/H] and [{alpha}/Fe], and that, even within a monoabundance population of stars, there are age variations that vary sensibly with Galactic position. Such stellar age constraints across the Milky Way open up new avenues in Galactic archeology.
15319. The Carina projects. I. Bright variables stars
ID:
ivo://CDS.VizieR/J/AJ/126/197
Title:
The Carina projects. I. Bright variables stars
Short Name:
J/AJ/126/197
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new BV time series data of the Carina dwarf spheroidal galaxy (dSph). Current data cover an area of ~0.3deg^2^ around the center of the galaxy and allow us to identify 92 variables. Among them 75 are RR Lyrae stars, 15 are bona fide anomalous Cepheids, one might be a Galactic field RR Lyrae star, and one is located along the Carina red giant branch. Expanding upon the seminal photographic investigation by Saha, Monet, & Seitzer (1986AJ.....92..302S) we supply, for the first time, accurate estimates of their pulsation parameters (periods, amplitudes, mean magnitudes, and colors) on the basis of CCD photometry. Approximately 50% of both RR Lyrae stars and anomalous Cepheids are new identifications. Among the RR Lyrae sample, six objects are new candidate double-mode (RRd) variables. On the basis of their pulsation properties we estimate that two variables (V158, V182) are about 50% more massive than typical RR Lyrae stars, while the bulk of the anomalous Cepheids are roughly a factor of 2 more massive than fundamental-mode (RRab) RR Lyrae stars.
15320. The Carina project. X. Radial velocities
ID:
ivo://CDS.VizieR/J/ApJ/830/126
Title:
The Carina project. X. Radial velocities
Short Name:
J/ApJ/830/126
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2200 low-resolution spectra collected with VIMOS at Very Large Telescope (VLT). The targets are faint (20<~V<~21.5mag), but the accuracy at the faintest limit is <=9km/s. These data were complemented with RV measurements either based on spectra collected with FORS2 and FLAMES/GIRAFFE at VLT or available in the literature. We ended up with a sample of 2748 stars and among them, 1389 are candidate Carina stars. We found that the intermediate-age stellar component shows a well-defined rotational pattern around the minor axis. The western and the eastern side of the galaxy differ by +5 and -4km/s when compared with the main RV peak. The old stellar component is characterized by a larger RV dispersion and does not show evidence of the RV pattern. We compared the observed RV distribution with N-body simulations for a former disky dwarf galaxy orbiting a giant Milky Way-like galaxy. We rotated the simulated galaxy by 60{deg} with respect to the major axis, we kept the observer on the orbital plane of the dwarf and extracted a sample of stars similar to the observed one. Observed and predicted V_rot_/{sigma} ratios across the central regions are in remarkable agreement. This evidence indicates that Carina was a disky dwarf galaxy that experienced several strong tidal interactions with the Milky Way. Owing to these interactions, Carina transformed from a disky to a prolate spheroid and the rotational velocity transformed into random motions.

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